Organic light emitting element, display apparatus having the same and method of manufacturing the same

ABSTRACT

An organic light emitting element is formed on the substrate. The organic light emitting element includes a first electrode, a bank, a surface energy, an organic light emitting member and a second electrode. The first electrode receives the first driving signal. The first electrode has a first surface energy. The bank surrounds sides of the first electrode. The surface energy lowering pattern is formed on the bank. The surface energy lowering pattern has a second surface energy that is lower than the first surface energy. The organic light emitting member is formed on the first electrode. The second electrode receives a second driving signal to display an image. Therefore, an image display quality of the display apparatus is improved.

CROSS-REFERENCE OF RELATED APPLICATIONS

The present application claims priority from Korean Patent ApplicationNo. 2003-82364, filed on Nov. 19, 2003, the disclosure of which ishereby incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an organic light emitting element, adisplay apparatus and a method of manufacturing the display apparatus.More particularly, the present invention relates to an organic lightemitting element capable of improving an image display quality, adisplay apparatus capable having the organic light emitting element, anda method of manufacturing the display apparatus.

2. Description of the Related Art

An information processing device has been improved, and has been widelyused in various fields.

Data processed by the information processing device is an electricsignal or a coded signal. However, a user may not directly recognize theelectric signal or the coded signal. The information processing devicehas a display apparatus so that the electric signal or the coded signalis displayed by the display apparatus.

The display apparatus is classified into an emissive display apparatusand a non-emissive display apparatus. The emissive display apparatusdisplays the image using luminescence. The emissive display apparatusincludes a cathode ray tube (CRT) display apparatus, a plasma displaypanel (PDP), a light emitting diode (LED), an inorganic light emittingdisplay apparatus, an organic light emitting display (OLED) apparatus,etc.

The non-emissive display apparatus displays the image using reflection,scattering or interference of a light. The non-emissive displayapparatus includes a liquid crystal display (LCD) apparatus, anelectrochemical display (ECD) apparatus, an electrophoretic imagedisplay (EPID) apparatus, etc.

The inorganic light emitting display apparatus and the OLED apparatushave been widely used.

Electrons are accelerated in a light emitting portion of the inorganiclight emitting display apparatus in strong electric field so that theaccelerated electrons are combined with inorganic material, and theinorganic material is in an excited state. When the excited material ischanged into a ground state, a light is generated in the light emittingportion.

The OLED apparatus has an organic light emitting layer formed between ananode electrode and a cathode electrode. Electrons from the anodeelectrode are combined with holes from the cathode electrode in theorganic light emitting layer so that molecules of the organic lightemitting layer are in the excited state. When the excited molecules arechanged into the ground state, the light is generated in the organiclight emitting layer.

The organic light emitting layer of the OLED apparatus may be formedthrough a screen printing method or a spray printing method. In thescreen printing method, organic light emitting material is printed on asubstrate through openings of a mask.

In the spray printing method, the organic light emitting material isdropped on a portion of the substrate. In particular, a bank is formedadjacent to the anode electrode that is formed on the substrate, and theorganic light emitting material is dropped in a space formed by thebank. The dropped organic light emitting material is dried to form theorganic light emitting layer.

When the organic light emitting material is dropped on the bank that hashigher surface energy than the anode electrode, the organic lightemitting layer may be formed on the bank so that the image displayquality is deteriorated. When the bank has higher surface energy thanthe anode electrode, the bank has higher adhesive force than the anodeelectrode.

Surface structure of the bank may be changed to decrease the surfaceenergy of the bank through an addition process. However, when theorganic light emitting layer has a double layered structure having ahole injection layer and a light emitting layer formed on the holeinjection layer, the surface energy of the bank may be changed after thehole injection layer being formed. When the light emitting layer isformed after the hole injection layer being formed, the surface energyof the bank is increased so that the light emitting layer may beattached to the bank. Therefore, the image display quality of the OLEDapparatus may be deteriorated.

BRIEF SUMMARY OF THE INVENTION

The present invention provides an organic light emitting element capableof improving an image display quality.

The present invention also provides a display apparatus having theabove-mentioned organic light emitting element.

The present invention also provides a method of manufacturing theabove-mentioned display apparatus.

An organic light emitting element in accordance with an aspect of thepresent invention is formed on a substrate. The organic light emittingelement includes a first electrode, a bank, a surface energy loweringpattern, an organic light emitting member and a second electrode. Thefirst electrode receives a first driving signal. The first electrode hasa first surface energy. The bank surrounds sides of the first electrode.The surface energy lowering pattern is formed on the bank. The surfaceenergy lowering pattern has a second surface energy that is lower thanthe first surface energy. The organic light emitting member is formed onthe first electrode. The second electrode receives a second drivingsignal to display an image.

A display apparatus in accordance with an aspect of the presentinvention includes a peripheral circuit and an organic light emittingelement. The peripheral circuit is formed on a substrate to generate afirst driving signal. The organic light emitting element is formed onthe substrate. The organic light emitting element includes a firstelectrode, a bank, a surface energy, an organic light emitting memberand a second electrode. The first electrode receives the first drivingsignal. The first electrode has a first surface energy. The banksurrounds sides of the first electrode. The surface energy loweringpattern is formed on the bank. The surface energy lowering pattern has asecond surface energy that is lower than the first surface energy. Theorganic light emitting member is formed on the first electrode. Thesecond electrode receives a second driving signal to display an image.

A display apparatus in accordance with another aspect of the presentinvention includes an organic light emitting element on a substrate. Theorganic light emitting element has a first electrode, a bank, a surfaceenergy lowering pattern, an organic light emitting member and a secondelectrode. The first electrode is configured to receive a first drivingsignal. The bank surrounds sides of the first electrode, the bank havinga first surface energy. The surface energy lowering pattern is formed onthe bank. The surface energy lowering pattern has a second surfaceenergy that is lower than the first surface energy. The organic lightemitting member is formed on the first electrode. The second electrodeis configured to receive a second driving signal to display an image.

A display apparatus in accordance with another aspect of the presentinvention includes a switching transistor, a driving transistor and anorganic light emitting element. The switching transistor is formed on asubstrate. The switching transistor has a first source/drain electrodeand a first gate electrode. The driving transistor is formed on thesubstrate. The driving transistor has a second source/drain electrodeand a second gate electrode electrically connected to the firstsource/drain electrode of the switching transistor. The organic lightemitting element is formed on the substrate having the switchingtransistor and the driving transistor. The organic light emittingelement has a first electrode, a bank, a surface energy loweringpattern, an organic light emitting member and a second electrode. Thefirst electrode is electrically connected to the second source/drainelectrode of the driving transistor. The bank is formed on the substratehaving the first electrode. The bank surrounds sides of the firstelectrode is to form a hole on the first electrode. The bank has a firstsurface energy. The surface energy lowering pattern is formed on thebank. The surface energy lowering pattern has a second surface energythat is lower than the first surface energy. The organic light emittingmember is formed on the first electrode. The second electrode is formedon the substrate having the organic light emitting member.

A method of manufacturing the display apparatus in accordance with anaspect of the present invention is provided as follows. A firstelectrode that has a first surface energy is formed on a base substrate.The first electrode receives a first driving signal from a peripheralcircuit. A bank that surrounds sides of the first electrode is formed onthe base substrate. A surface energy lowering pattern is formed on thebank. The surface energy lowering pattern has a second surface energythat is lower than the first surface energy. An organic light emittingmember is formed on the first electrode. A second electrode is formed onthe organic light emitting member. The second electrode receives asecond driving signal to display an image.

According to this present invention, when an organic light emittingmaterial is dropped in a hole surrounded by a bank on an electrode, theorganic light emitting material may not be attached to the bank so thatan image display quality of a display apparatus is improved.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other advantages of the present invention will become moreapparent by describing in detail exemplary embodiments thereof withreference to the accompanying drawings, in which:

FIG. 1 is a circuit diagram showing a display apparatus in accordancewith an exemplary embodiment of the present invention;

FIG. 2 is a partially cutout perspective view showing an organic lightemitting display (0OLED) apparatus in accordance with an exemplaryembodiment of the present invention;

FIG. 3 is a cross-sectional view taken along a line I-I′ shown in FIG.2;

FIG. 4 is an enlarged cross-sectional view showing a portion ‘B’ shownin FIG. 3;

FIG. 5 is an enlarged cross-sectional view showing a portion ‘C’ shownin FIG. 3;

FIGS. 6A to 6I are cross-sectional views showing a method ofmanufacturing a display apparatus in accordance with an exemplaryembodiment of the present invention; and

FIG. 7 is a cross-sectional view showing a method of manufacturing adisplay apparatus in accordance with another exemplary embodiment of thepresent invention.

DESCRIPTION OF THE EMBODIMENTS

It should be understood that the exemplary embodiments of the presentinvention described below may be varied modified in many different wayswithout departing from the inventive principles disclosed herein, andthe scope of the present invention is therefore not limited to theseparticular following embodiments. Rather, these embodiments are providedso that this disclosure will be through and complete, and will fullyconvey the concept of the invention to those skilled in the art by wayof example and not of limitation.

Hereinafter, the present invention will be described in detail withreference to the accompanying drawings.

FIG. 1 is a circuit diagram showing a display apparatus in accordancewith an exemplary embodiment of the present invention.

Referring to FIG. 1, the display apparatus 300 includes a peripheralcircuit 100 and an organic light emitting element 200. The peripheralcircuit 100 and the organic light emitting element 200 are formed on asubstrate 10.

The peripheral circuit 100 includes a switching transistor TFT1, adriving transistor TFT2, a storage capacitor C_(st), a gate bus lineGBL, a data bus line DBL and a power supply line PSL.

The gate bus line GBL is extended in a first direction. The gate busline GBL has low resistance. The gate bus line GBL includes aluminum,aluminum alloy, etc.

A plurality of the gate bus lines GBLs may be formed on the substrate10. In this exemplary embodiment, the display apparatus 300 displaysfull-color image, and the display apparatus 300 has a resolution of1024×768. In addition, the display apparatus 300 has 768 gate bus linesGBLs.

Each of the gate bus lines GBLs is extended in the first direction. Thegate bus lines GBLs are arranged in a second direction that issubstantially perpendicular to the first direction.

A gate electrode GE is electrically connected to each of the gate buslines GBLs. The gate electrode GE is extended in the second direction.In this exemplary embodiment, number of the gate electrodes GEs is1024×3, and the gate electrodes GEs are spaced apart from one another bya predetermined interval.

The data bus line DBL is extended in the second direction. The data busline DBL has low resistance. The data bus line DBL includes aluminum,aluminum alloy, etc.

A plurality of the data bus lines DBLs may be formed on the substrate10. In this exemplary embodiment, number of the data bus lines DBLs is1024×3. Each of the data bus lines DBLs is extended in the seconddirection. The data bus lines DBLs are arranged in the first direction.

A source electrode SE is electrically connected to each of the data buslines DBLs. The source electrode SE is extended in the first direction.In this exemplary embodiment, number of the source electrodes SEs is768, and the source electrodes SEs are spaced apart from one another bya predetermined interval.

The power supply line PSL is spaced apart from each of the data buslines DBLs. The power supply line PSL is extended in the seconddirection. A direct current signal VDD is applied to the power supplyline PSL.

The switching transistor TFT1 and the driving transistor TFT2 are formedin a pixel region 110. The pixel region 110 is defined by the gate buslines GBLs disposed adjacent to each other, each of the data bus linesDBLs and each of the power supply lines PSLs.

The switching transistor TFT1 includes a first gate electrode G1, afirst semiconductor pattern C1, a first source electrode S1 and a firstdrain electrode D1.

The first gate electrode G1 is electrically connected to each of thegate electrodes GEs that are electrically connected to the gate buslines GBLs.

The first semiconductor pattern C1 is electrically insulated from thefirst gate electrode G1 by an insulating layer (not shown) havinginsulating material. The first semiconductor pattern C1 is formed on theinsulating layer (not shown) corresponding to the first gate electrodeG1.

The first source electrode S1 is disposed on the first semiconductorpattern C1, and electrically connected to each of the source electrodesSEs that are electrically connected to the data bus line DBLs.

The driving transistor TFT2 is formed in the pixel region 110. Thedriving transistor TFT2 includes a second gate electrode G2, a secondsemiconductor pattern C2, a second source electrode S2 and a seconddrain electrode D2.

The second gate electrode G2 is electrically connected to the firstdrain electrode D1 of the switching transistor TFT1.

The second semiconductor pattern C2 is electrically insulated from thesecond gate electrode G2 by the insulating layer (not shown) having theinsulating material. The second semiconductor pattern C2 is formed onthe insulating layer (not shown) corresponding to the second gateelectrode G2.

The second source electrode S2 is formed on the second semiconductorpattern C2, and electrically connected to each of the power supply linesPSLs.

The second drain electrode D2 is formed on the second semiconductorpattern C2, and spaced apart from the second source electrode S2. Thesecond drain electrode D2 is electrically connected to the organic lightemitting element 200.

The storage capacitor C_(st) includes a first capacitor electrodeC_(st1), a second capacitor electrode C_(st2) and a dielectric layer.The first capacitor electrode C_(st1) is electrically connected to thesecond gate electrode G2. The second capacitor electrode C_(st2) iselectrically connected to each of the power supply lines PSLs. Thedielectric layer is disposed between the first and second capacitorelectrodes C_(st1) and C_(st2). The dielectric layer may be aninsulating layer. The storage capacitor C_(st) maintains a voltagedifference between the second gate electrode G2 and each of the powersupply lines PSLs to turn on the second gate electrode G2 for one frame.

When a turn-on voltage is applied to each of the gate bus lines GBLs,and an image signal is applied to each of the data bus lines DBLs, theimage signal is applied to the first drain electrode D1 through thefirst source electrode S1 of the switching transistor TFT1 and the firstsemiconductor pattern C1.

The image signal outputted from the first drain electrode D1 is appliedto the second gate electrode G2 of the driving transistor TFT2 so thatthe second semiconductor pattern C2 is turned on. The resistance of thesecond semiconductor pattern C2 varies based on a level of the imagesignal that is applied to the second gate electrode G2. When the secondsemiconductor pattern C2 is turned on, the direct current signaloutputted from the power supply line PSL is applied to the second drainelectrode D2 through the second source electrode S2 and the secondsemiconductor pattern C2. The level of the direct current voltageoutputted from the power supply line PSL is decreased based on theresistance of the second semiconductor pattern C2. Therefore, a firstdriving signal that has a level corresponding to the image signal isapplied to the second drain electrode D2.

FIG. 2 is a partially cutout perspective view showing an organic lightemitting display (OLED) apparatus in accordance with an exemplaryembodiment of the present invention.

Referring to FIGS. 1 and 2, the organic light emitting element 200includes a first electrode 210, a bank 220, a surface energy loweringpattern 230, an organic light emitting layer 240 and a second electrode250.

The first driving signal outputted from the second drain electrode D2 ofthe driving transistor TFT2 is applied to the first electrode 210. Thefirst electrode 210 has a transparent conductive material such as indiumtin oxide (ITO), tin oxide (TO), indium zinc oxide (IZO), zinc oxide(ZO), etc. The first electrode 210 may be electrically connected to thesecond drain electrode D2 through a contact hole.

A plurality of the first electrodes 210 may be arranged in a matrixshape on the substrate 10. In this exemplary embodiment, the resolutionof the display apparatus 300 is 1024×768, and the display apparatus has1024×768×3 first electrodes 210.

Each of the first electrodes 210 has a first surface energy. The firstsurface energy varies based on the material of the first electrodes 210.When the surface energy is increased, a frictional force and an adhesiveforce between the first electrodes 210 and a fluid are increased. Inaddition, when the surface energy is decreased, a frictional force andan adhesive force between the first electrodes 210 and the fluid aredecreased.

FIG. 3 is a cross-sectional view taken along a line I-I′ shown in FIG.2. FIG. 4 is an enlarged cross-sectional view showing a portion ‘B’shown in FIG. 3.

Referring to FIGS. 2 to 4, the bank 220 surrounds sides of each of thefirst electrodes 210 on the substrate 10 to form a hole 225. The bank220 may have a wall shape. In this exemplary embodiment, the bank 220has a trapezoidal cross-section. A surface of the bank 220 forms a taperangle of about 60° to about 150° with respect to a surface of each ofthe first electrodes 210. The bank 220 may be formed through a photoprocess using a photosensitive material. The photosensitive material mayinclude a positive photoresist, a negative photoresist, etc.Alternatively, an organic layer (not shown) or an inorganic layer (notshown) is patterned through a photolithography to form the bank. Thatis, the organic layer (not shown) or the inorganic layer (not shown) maybe deposited on the substrate, and the deposited layer may be patternedthrough a photo process and an etching process.

In this exemplary embodiment, the bank 220 has lower surface energy thanthe first electrodes 210. When the bank 220 has higher surface energythan the first electrodes, the organic light emitting layer 240 may beformed on the bank 220 so that an image display quality of the displayapparatus is deteriorated.

The surface energy lowering pattern 230 is formed on the bank 220. Thesurface energy lowering pattern 230 may be formed on a whole surface ofthe bank 220, a portion of the bank 220 or only top surface of the bank220. A contact angle of the surface energy lowering pattern 230 is noless than about 40° with respect to water.

The surface energy lowering pattern 230 has a second surface energy thatis lower than the first electrodes 210 and the bank 220. The surfaceenergy lowering pattern 230 includes a synthetic resin having fluorine,a fluorine-containing compound such as SF₆, CF₄, oxygen, etc. Thesynthetic resin may be an epoxy resin, a silicone resin, an acrylicresin, an urethane resin, a phenolic resin, polyethylene, polypropylene,polystyrene, polymethyl metacrylate, polyurea, polyimide, etc. In thisexemplary embodiment, the surface energy lowering film 238 has the epoxyresin containing fluorine. The surface energy lowering pattern 230 maybe formed on the bank 220 as a thin film shape. Alternatively, liquidhaving the fluorine or the fluorine compound may be coated on the bank220 to form the surface energy lowering pattern 230.

The second surface energy of the surface energy lowering pattern 230 maynot be changed during a manufacturing process of the display apparatus.That is, the second surface energy of the surface energy loweringpattern 230 may not be changed though a predetermined time has passed.

FIG. 5 is an enlarged cross-sectional view showing a portion ‘C’ shownin FIG. 3.

Referring to FIGS. 3 and 5, the organic light emitting layer 240 isformed in the hole 225 formed by the bank 220 that has the surfaceenergy lowering pattern 230. In this exemplary embodiment, the organiclight emitting layer 240 has a hole injection layer 242 and a lightemitting layer 244.

In order to form the hole injection layer 242, a liquid that forms thehole injection layer 242 is dropped in the hole 225. The dropped liquidis dried to form the hole injection layer 242 on the first electrode210. In this exemplary embodiment, the liquid is not dropped on the bank220 by a repellent force between the dropped liquid and the bank 220.The repellent force is caused by the low surface energy of the surfaceenergy lowering pattern 230. Alternatively, the liquid may be dropped ona portion of the bank 220.

In order to form the light emitting layer 244, an organic material thatforms the light emitting layer 244 is dropped in the hole 225 in whichthe hole injection layer 242 is formed. The dropped organic material isdried to form the light emitting layer 244. In this exemplaryembodiment, the light emitting layer 244 is not formed on the bank 220.

The second electrode 250 is formed on the substrate 10 having theorganic light emitting layer 240. A second driving signal is applied tothe second electrode 250 to display the image. In this exemplaryembodiment, the second electrode 250 has aluminum, aluminum alloy, etc.The second electrode 250 may be formed through a sputtering method, achemical deposition method, etc.

FIGS. 6A to 6I are cross-sectional views showing a method ofmanufacturing a display apparatus in accordance with an exemplaryembodiment of the present invention. A peripheral circuit is formedbefore a first electrode is formed. The peripheral circuit has two thinfilm transistors, one capacitor, a gate bus line, a data bus line and apower supply line. The peripheral circuit of FIGS. 6A and 6I is same asin FIGS. 1 to 5. Thus, the same reference numerals will be used to referto the same or like parts as those described in FIGS. 1 to 5 and anyfurther explanation will be omitted.

Referring to FIG. 6A, first electrodes 210 are formed on the substrate10 having the peripheral circuit 100. The transparent conductivematerial such as indium tin oxide (ITO), indium zinc oxide (IZO), etc.,is deposited on the substrate 10 having the peripheral circuit 100. Thedeposited transparent conductive material is patterned to form the firstelectrodes 210. In this exemplary embodiment, a resolution of thedisplay apparatus 300 is 1024×764, and number of the first electrodes210 is 1024×764×3. The first electrodes 210 are arranged in a matrixshape. The first electrodes 210 are spaced apart from one another by apredetermined interval G. The first electrode 210 has a first surfaceenergy.

Referring to FIG. 6B, a photosensitive thin film is formed on the firstsubstrate 10 through a spin coating method. A thickness of thephotosensitive thin film is about 3 μm. The photosensitive thin film isexposed by a light, and developed by a developer solution so that thephotosensitive thin film is patterned to form the bank 220. The bank 220surrounds sides of each of the first electrodes 210 to form the hole 225on each of the first electrodes 210. The bank 220 is then baked so thatthe bank 220 may not be changed by the light.

Referring to FIG. 6C, a surface energy lowering printing sheet 231 isformed on the bank 220.

The surface energy lowering printing sheet 231 has a base film 233, aconversion film 235 and a surface energy lowering film 238. The basefilm 233 includes triacetylcellulose (TAC), polycarbonate (PC),polyethersulfone (PES), polyethyleneterephthalate (PET),polyethylenenaphthalate (PEN), polyvinylalcohol (PVA),polymethylmethacrylate (PMMA), cyclo-olefin polymer (COP), etc. Theconversion film 235 is formed on the base film 233. The conversion film235 includes isocynate, vinyl acetate, polyester, polyvinyl alcohol,acrylate, etc. In this exemplary embodiment, the conversion film 235 hasthe vinyl acetate. The surface energy lowering film 238 is formed on theconversion film 235. The surface energy lowering film 238 includes asynthetic resin having fluorine, a fluorine-containing compound, oxygen,etc. The synthetic resin may be an epoxy resin, a silicone resin, anacrylic resin, an urethane resin, a phenolic resin, polyethylene,polypropylene, polystyrene, polymethyl metacrylate, polyurea, polyimide,etc. In this exemplary embodiment, the surface energy lowering film 238has the epoxy resin containing fluorine. When the light or a laser beamis irradiated onto the conversion film 235, a heat is generated in theconversion film 235. The surface energy lowering film 238 has fluorineor the fluorine-containing compound so that the surface energy loweringfilm 238 has lower surface energy than the bank 220 and the firstelectrodes 210.

In this exemplary embodiment, the surface energy lowering film 238 isdetached from the conversion film 235, and has a second surface energythat is lower than the first surface energy.

The surface energy lowering film 238 of the surface energy loweringprinting sheet 231 is formed on the bank 220. A laser beam 239 isselectively irradiated onto an upper surface of the bank 220.

The laser beam 239 passes through the base film 233, and the laser beam239 is irradiated onto the conversion film 235. The heat is generatedfrom the conversion film 235, and the heat is transferred into thesurface energy lowering film 238.

Referring to FIG. 6D, the heated portion of the surface energy loweringfilm 238 is detached from a remaining portion of the surface energylowering film 238 and the conversion film 235 so that the surface energylowering pattern 230 is formed on the bank 220.

Referring to FIG. 6E, a hole injection composition 241 that has highfluidity is dropped in the hole 225 on each of the first electrodes 210.The hole injection composition 241 has a hole injection material, avolatile solvent, additives, etc. The volatile material may be propyleneglycol monomethyl ether, propylene glycol monomethyl ether acetate,ethylene glycol monomethyl ether acetate, ethyl ethoxy propionate,cyclohexanone, diethylene glycol dimethyl ether, etc., or combinationsthereof.

The dropped hole injection composition 241 is dried so that the volatilematerial is evaporated. When the volatile material is evaporated, sizeand height of the hole injection composition 241 are decreased. The bank220 has lower surface energy than the surface energy lowering pattern230 so that the hole injection composition 241 may not be attached tothe bank 220.

Referring to FIG. 6F, the hole injection layer 242 having a thin filmshape is formed on each of the first electrodes 210.

Referring to FIG. 6G, a light emitting composition 243 that has highfluidity is dropped in the hole 225 on the hole injection layer 242. Thelight emitting composition 243 has a light emitting material, a volatilesolvent, additives, etc. The volatile solvent may be propylene glycolmonomethyl ether, propylene glycol monomethyl ether acetate, ethyleneglycol monomethyl ether acetate, ethyl ethoxy propionate, cyclohexanone,diethylene glycol dimethyl ether, etc., or combinations thereof.

The dropped light emitting composition 243 is dried so that the volatilematerial in the dropped light emitting composition 243 is evaporated.When the volatile material is evaporated, size and height of the lightemitting composition 243 are decreased. The bank 220 is has lowersurface energy than the surface energy lowering pattern 230 so that thelight emitting composition 243 may not be attached to the bank 220.

Referring to FIG. 6H, the light emitting layer 244 having a thin filmshape is formed on the hole injection layer 242. The hole injectionlayer 242 and the light emitting layer 244 form the organic lightemitting layer 240.

Referring to FIG. 6I, the second electrode 250 is formed on thesubstrate 10. The second electrode 250 may include aluminum, aluminumalloy, etc. The second electrode 250 is formed on the bank 220 and theorganic light emitting layer 240 so that the organic light emittinglayer 240 is electrically connected to the second electrode 250. Inorder to display the image, a second driving signal is applied to thesecond electrode 250.

FIG. 7 is a cross-sectional view showing a method of manufacturing adisplay apparatus in accordance with another exemplary embodiment of thepresent invention. The method of FIG. 7 is same as in FIGS. 6A to 6I.Thus, the same reference numerals will be used to refer to the same orlike parts as those described in FIGS. 6A to 6I and any furtherexplanation will be omitted.

Referring to FIG. 7, a roller 238 b is disposed on a bank 220. A surfaceenergy lowering material 238 a is coated on an outer surface of theroller 238 b. The coated surface energy lowering material 238 a isdisposed between the roller 238 b and the bank 220.

The roller 238 b rotates in a predetermined direction so that the coatedsurface energy lowering material 238 a is coated on the bank 220 to formthe surface energy lowering coating film 238.

According to the present invention, when an organic light emittingmaterial is dropped in a hole surrounded by a bank on an electrode, theorganic light emitting material may not be attached to the bank so thatan image display quality of a display apparatus is improved.

This invention has been described with reference to the exemplaryembodiments. It is evident, however, that many alternative modificationsand variations will be apparent to those having skill in the art inlight of the foregoing description. Accordingly, the present inventionembraces all such alternative modifications and variations as fallwithin the spirit and scope of the appended claims.

1. An organic light emitting element on a substrate, the organic lightemitting element comprising: a first electrode configured to receive afirst driving signal, the first electrode having a first surface energy;a bank that surrounds sides of the first electrode; a surface energylowering pattern on the bank, the surface energy lowering pattern havinga second surface energy that is lower than the first surface energy; anorganic light emitting member on the first electrode; and a secondelectrode configured to receive a second driving signal to display animage.
 2. The organic light emitting element of claim 1, wherein thesurface energy lowering pattern is formed on a top surface of the bank.3. The organic light emitting element of claim 1, wherein the bankcomprises a third surface energy that is higher than the second surfaceenergy.
 4. A display apparatus comprising: an organic light emittingelement on a substrate, the organic light emitting element including: afirst electrode configured to receive a first driving signal, the firstelectrode having a first surface energy; a bank that surrounds sides ofthe first electrode; a surface energy lowering pattern on the bank, thesurface energy lowering pattern having a second surface energy that islower than the first surface energy; an organic light emitting member onthe first electrode; and a second electrode configured to receive asecond driving signal to display an image.
 5. The display apparatus ofclaim 4, wherein the surface energy lowering pattern is formed on a topsurface of the bank.
 6. The display apparatus of claim 4, wherein thebank: comprises a third surface energy that is higher than the secondsurface energy.
 7. The display apparatus of claim 4, wherein the displayapparatus comprises a plurality of first electrodes arranged in a matrixshape, and each of the first electrodes has indium tin oxide, tin oxide,indium zinc oxide or zinc oxide.
 8. The display apparatus of claim 4,wherein the bank surrounds the sides of the first electrode to form ahole on the first electrode.
 9. The display apparatus of claim 4,wherein a surface of the bank forms a taper angle of about 60° to about150° with respect to a surface of the first electrode.
 10. The displayapparatus of claim 4, wherein the surface energy lowering film comprisesfluorine.
 11. The display apparatus of claim 4, wherein the organiclight emitting member comprises a hole injection layer and a lightemitting layer on the hole injection layer.
 12. The display apparatus ofclaim 4, wherein the second electrode comprises a metal.
 13. A displayapparatus comprising: an organic light emitting element on a substrate,the organic light emitting element including: a first electrodeconfigured to receive a first driving signal; a bank that surroundssides of the first electrode, the bank having a first surface energy; asurface energy lowering pattern on the bank, the surface energy loweringpattern having a second surface energy that is lower than the firstsurface energy; an organic light emitting member on the first electrode;and a second electrode configured to receive a second driving signal todisplay an image.
 14. A display apparatus comprising: a switchingtransistor on a substrate, the switching transistor having a firstsource/drain electrode and a first gate electrode; a driving transistoron the substrate, the driving transistor having a second source/drainelectrode and a second gate electrode electrically connected to thefirst source/drain electrode of the switching transistor; and an organiclight emitting element on the substrate having the switching transistorand the driving transistor, the organic light emitting elementincluding: a first electrode electrically connected to the secondsource/drain electrode of the driving transistor; a bank on thesubstrate having the first electrode, the bank surrounding sides of thefirst electrode to form a hole on the first electrode, the bank having afirst surface energy; a surface energy lowering pattern on the bank, thesurface energy lowering pattern having a second surface energy that islower than the first surface energy; an organic light emitting member onthe first electrode; and a second electrode on the substrate having theorganic light emitting member.
 15. The display apparatus of claim 14,wherein the first electrode comprises a third surface energy that ishigher than the second surface energy.
 16. The display apparatus ofclaim 14, wherein the surface energy lowering pattern is formed on a topsurface of the bank. 17-28. (canceled)